Hinge Mortise Templates

Q.What's the advantage of
using a router fitted with a template guide bushing to
cut hinge mortises? Why not just use a flush-cutting
pilot bit and a flush-type template?

A.Gary Katz, a finish
carpenter in Reseda, Calif., and moderator of
jlconline.com's finish-carpentry forum,
responds: Whenever I'm duplicating a shape
with a pattern template, I generally like to use a
pilot — or pattern — bit guided
by a top- or bottom-mounted bearing that matches
the diameter of the cutters.

An advantage of this setup is that the template
can be made to exactly match the size and shape of
the workpiece; there's no need to calculate
offsets. And because the bit is going around the
outside of the pattern, sawdust buildup interfering
with the cutter is rarely a problem.

But when I cut mortises with a router and a
template — for hinges, locks, and other
hardware or joinery — I prefer to use a
template guide bushing and a regular mortising bit
in my router rather than a bearing-guided bit. This
mortising method offers several advantages.

First, when you're cutting a mortise, the router
bit must be inserted inside the template, so a
template guide bushing protects the interior walls
of the template from being nicked. Also, when
you're using a template guide bushing, the template
opening has to be oversized to accommodate the
bushing's outside dimension, which is a good thing
because sawdust waste builds up inside a mortise
template. Having a template that's 1/8 inch to 1/4
inch larger than the mortise allows a little extra
room for this waste, making it easier to cut
mortises quickly and cleanly.

In addition, the template kits of some
manufacturers feature template guide bushings that
are easy to remove in mid-operation, making it
possible to switch quickly from one bushing to
another of a different size. This is something I do
frequently, particularly when I need a mortise that
steps down deeper once the plate size is cut (for
pocket pulls and some flush bolts, for
instance).